U.S. patent application number 12/528921 was filed with the patent office on 2010-03-18 for hydrogen generator and fuel cell system.
Invention is credited to Hideo Ohara, Masataka Ozeki, Kiyoshi Taguchi, Yoshio Tamura.
Application Number | 20100068573 12/528921 |
Document ID | / |
Family ID | 40853087 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100068573 |
Kind Code |
A1 |
Tamura; Yoshio ; et
al. |
March 18, 2010 |
HYDROGEN GENERATOR AND FUEL CELL SYSTEM
Abstract
A hydrogen generator (100) includes: a reformer (1) configured
to generate a hydrogen-containing gas using a raw material and
steam; a water evaporator (4) configured to supply the steam to the
reformer (1); a sealing device (10) provided on a passage located
downstream of the reformer (1) and configured to block a gas in the
passage from flowing to the atmosphere; and a depressurizer (3)
provided on a passage located upstream of the reformer (1) and
configured to release to the atmosphere, pressure in the hydrogen
generator (100) which pressure is increased by water evaporation in
the water evaporator (4) after the sealing device (10) is
closed.
Inventors: |
Tamura; Yoshio; (Hyogo,
JP) ; Taguchi; Kiyoshi; (Osaka, JP) ; Ozeki;
Masataka; (Osaka, JP) ; Ohara; Hideo; (Osaka,
JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, NW
WASHINGTON
DC
20005-3096
US
|
Family ID: |
40853087 |
Appl. No.: |
12/528921 |
Filed: |
January 9, 2009 |
PCT Filed: |
January 9, 2009 |
PCT NO: |
PCT/JP2009/000066 |
371 Date: |
August 27, 2009 |
Current U.S.
Class: |
429/420 ;
422/113; 422/117 |
Current CPC
Class: |
Y02E 60/50 20130101;
C01B 2203/0811 20130101; H01M 8/04225 20160201; C01B 2203/0233
20130101; C01B 2203/1288 20130101; H01M 8/0618 20130101; C01B 3/384
20130101; Y02P 20/10 20151101; C01B 2203/1609 20130101; C01B
2203/1235 20130101; C01B 2203/1247 20130101; H01M 8/04223 20130101;
C01B 2203/0822 20130101; C01B 2203/0827 20130101; H01M 8/04089
20130101; C01B 2203/1628 20130101; C01B 2203/127 20130101; C01B
2203/066 20130101; H01M 8/0662 20130101 |
Class at
Publication: |
429/19 ; 422/113;
422/117 |
International
Class: |
C01B 3/32 20060101
C01B003/32; H01M 8/18 20060101 H01M008/18; C01B 3/38 20060101
C01B003/38; G05D 16/00 20060101 G05D016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 9, 2008 |
JP |
2008-002311 |
Claims
1. A hydrogen generator comprising: a reformer configured to
generate a hydrogen-containing gas using a raw material and steam;
a water evaporator configured to supply the steam to the reformer;
and a sealing device provided on a passage located downstream of
the reformer and configured to block a gas in the passage from
flowing to atmosphere, the hydrogen generator further comprising a
depressurizer provided on a passage located upstream of the
reformer and configured to release to the atmosphere, pressure in
the hydrogen generator which pressure is increased by water
evaporation in the water evaporator after the sealing device is
closed.
2. The hydrogen generator according to claim 1, wherein the
depressurizer is provided on the passage which connects the water
evaporator and the reformer.
3. The hydrogen generator according to claim 1, further comprising
a raw material supplier configured to supply the raw material to
the reformer, wherein the depressurizer is provided on the passage
which connects the raw material supplier and the reformer.
4. The hydrogen generator according to claim 1, wherein the
depressurizer is provided on the passage located upstream of the
water evaporator.
5. The hydrogen generator according to claim 4, further comprising
a water supplier configured to supply water to the water
evaporator, wherein the depressurizer is provided on the passage
which connects the water supplier and the water evaporator.
6. The hydrogen generator according to claim 4, further comprising
a raw material supplier configured to supply the raw material to
the reformer, wherein the depressurizer is provided on the passage
which connects the raw material supplier and the water
evaporator.
7. The hydrogen generator according to claim 3, further comprising:
a deodorizer configured to remove an odorous component in the raw
material supplied to the reformer; and an on-off valve provided on
a passage extending between the deodorizer and the reformer,
wherein: the on-off valve is configured to block the gas from
flowing from the reformer to the deodorizer when the sealing device
is closed; and the depressurizer is provided on the passage which
connects the deodorizer and the reformer.
8. The hydrogen generator according to claim 1, wherein the sealing
device is a normally closed valve.
9. The hydrogen generator according to claim 1, wherein the
depressurizer is a valve including a relief mechanism capable of
releasing the pressure in the hydrogen generator to the atmosphere
in a case where the pressure in the hydrogen generator is a first
upper limit pressure or higher.
10. The hydrogen generator according to claim 1, wherein the
depressurizer is a solenoid valve including a spring sealing
mechanism and is configured to cancel sealing of the spring sealing
mechanism in a case where the pressure in the hydrogen generator is
the first upper limit pressure or higher.
11. The hydrogen generator according to claim 10, further
comprising: a pressure detector configured to detect the pressure
in the hydrogen generator sealed by the sealing device; and a
control unit configured to cause the sealing device to release the
pressure in the hydrogen generator to the atmosphere in a case
where the pressure detected by the pressure detector is equal to or
higher than a second upper limit pressure that is lower than the
first upper limit pressure.
12. The hydrogen generator according to claim 10, wherein during at
least one of a start-up standby period of the hydrogen generator
and a start-up operation of the hydrogen generator, the solenoid
valve carries out an open-close operation once in at least one of a
predetermined cumulative operating time, a predetermined cumulative
number of times of operations, a predetermined period of time, and
a predetermined consecutive start-up standby time.
13. The hydrogen generator according to claim 1, further
comprising: a pressure detector configured to detect the pressure
in the hydrogen generator sealed by the sealing device; and a
control unit, wherein: the depressurizer is an on-off valve; and
the control unit causes the on-off valve to open in a case where
the pressure detected by the pressure detector is a second upper
limit pressure or higher.
14. The hydrogen generator according to claim 13, wherein: the
on-off valve includes a relief mechanism capable of releasing the
pressure in the hydrogen generator to the atmosphere in a case
where the pressure in the hydrogen generator is a first upper limit
pressure or higher; and the second upper limit pressure is lower
than the first upper limit pressure.
15. The hydrogen generator according to claim 1, further
comprising: a falling slope passage through which the gas
discharged from the depressurizer is introduced downward; and a
receiver configured to receive the water discharged from a lower
end of the falling slope passage.
16. The hydrogen generator according to claim 15, wherein: the
receiver includes a water storing portion configured to store the
water and a discharging mechanism configured to discharge the water
stored in the water storing portion; and condensed water is wasted
to an outside of the hydrogen generator by discharging the water
using the discharging mechanism.
17. The hydrogen generator according to claim 16, wherein the
receiver includes a releasing structure capable of releasing to the
atmosphere the gas discharged from the lower end of the falling
slope passage.
18. A fuel cell system comprising: the hydrogen generator according
to claim 1; and a fuel cell configured to generate electric power
by using the hydrogen-containing gas supplied from the hydrogen
generator.
19. The hydrogen generator according to claim 6, further
comprising: a deodorizer configured to remove an odorous component
in the raw material supplied to the reformer; and an on-off valve
provided on a passage extending between the deodorizer and the
reformer, wherein: the on-off valve is configured to block the gas
from flowing from the reformer to the deodorizer when the sealing
device is closed; and the depressurizer is provided on the passage
which connects the deodorizer and the reformer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hydrogen generator
configured to generate a hydrogen-containing gas from a
hydrocarbon-based raw material and water by a steam-reforming
reaction. In addition, the present invention also relates to a fuel
cell system configured to generate electric power using hydrogen
generated by the hydrogen generator and oxygen.
BACKGROUND ART
[0002] A fuel cell system capable of carrying out highly-efficient,
small-scale electric power generation has been expected as a
distributed power generating system capable of realizing high
energy use efficiency, since it is easy to configure a system for
utilizing heat energy generated when a fuel cell generates electric
power.
[0003] In the electric power generating operation of the fuel cell
system, a hydrogen-containing gas and air (oxidizing gas) are
supplied to a fuel cell stack (hereinafter simply referred to as
"fuel cell") provided as a main body of an electric power
generating portion of the fuel cell system. Then, an
electrochemical reaction using hydrogen contained in the
hydrogen-containing gas supplied to the fuel cell and oxygen
contained in the air supplied to the fuel cell proceeds in the fuel
cell. By the progress of the electrochemical reaction, chemical
energies of the hydrogen and the oxygen are directly converted into
an electric energy in the fuel cell. Thus, the fuel cell system can
output electric power to a load.
[0004] Here, a system for supplying the hydrogen-containing gas
necessary during the electric power generating operation of the
fuel cell system is not developed as an infrastructure. Therefore,
a conventional fuel cell system is provided with a hydrogen
generator configured to generate the hydrogen-containing gas
necessary during the electric power generating operation. The
hydrogen generator includes at least a reformer. By the progress of
a steam-reforming reaction in a reforming catalyst body provided in
the reformer, the hydrogen-containing gas is generated from the raw
material, such as a city gas containing an organic compound, and
water. In this case, the reforming catalyst body of the reformer is
heated by a suitable heating device to a temperature suitable for
the progress of the steam-reforming reaction. For example, since
the heating device (burner, or the like) can combusts a mixture gas
of the city gas and the air, the reforming catalyst body of the
reformer can be heated by a high-temperature flue gas. In addition,
in the electric power generating operation of the fuel cell, an
anode off gas unconsumed in the fuel cell can be combusted in the
above-described burner. Thus, the reformer having been heated to
have a suitable temperature can efficiently generate the
hydrogen-containing gas by the reforming reaction between the raw
material, such as the city gas, and the steam.
[0005] The steam is generated by using a water evaporator provided
in the hydrogen generator and is used in the reforming reaction of
the reformer.
[0006] Moreover, while the fuel cell stops operating, input
portions and output portions of gases (the raw material, the
hydrogen-containing gas, and the oxidizing gas) and reforming water
are sealed to prevent gas passages of the hydrogen generator and
reactant gas passages of the fuel cell from being communicated with
the atmosphere. By sealing these portions, it is possible to
prevent outside air from getting into the fuel cell and the
hydrogen generator.
[0007] Meanwhile, with the input portions and the output portions
completely sealed, an internal state of the fuel cell system may
become an excessive positive pressure state or an excessive
negative pressure state with respect to the atmospheric
pressure.
[0008] Especially, in a case where the communication between an
internal space of the hydrogen generator and the outside air is
blocked while the hydrogen generator stops operating, i.e., in a
case where a sealed state of the hydrogen generator is realized
while the hydrogen generator stops operating, an excessive pressure
applied state of the hydrogen generator may occur by a volume
expansion caused due to water evaporation in the water evaporator.
Here, by open-close control of, for example, a solenoid valve for
sealing, the inside of the hydrogen generator is temporarily open
to the atmosphere to depressurize the inside of the hydrogen
generator (see Patent Document 2 for example).
[0009] Specifically, Patent Document 2 (for example, paragraph
0039) describes a method in which: a controller of the hydrogen
generator detects the increase in the internal pressure of the
hydrogen generator; and if the internal pressure abnormally
increases, an on-off valve provided downstream of the reformer is
temporarily open to discharge an internal gas of the hydrogen
generator to an outside of the hydrogen generator.
[0010] Moreover, in a case where the temperature of the hydrogen
generator is decreased after the sealed state is realized, and this
causes the negative pressure state, a predetermined amount of the
raw material is forcibly supplied to the inside of the fuel cell
system to pressurize the inside of the fuel cell system.
[0011] These depressurizing and pressurizing operations are
hereinafter referred to as a pressure keeping operation of the
hydrogen generator. By the pressure keeping operation, the
operation of the hydrogen generator can be appropriately stopped
while preventing the internal pressure of the hydrogen generator
from being applied to devices, i.e., maintaining the internal
pressure of the hydrogen generator at an appropriate level.
[0012] In a case where power supply to the hydrogen generator is
cut by power outage or the like during the operation of the
hydrogen generator, and this stops the operation of the hydrogen
generator, the increased internal pressure of the hydrogen
generator cannot be released to the atmosphere by the method
described in Patent Document 2.
[0013] Here, Patent Document 1 proposes a fuel cell system in which
a water sealing mechanism is provided on a passage by which the
hydrogen generator and the heater are communicated with each
other.
[0014] In accordance with the fuel cell system described in Patent
Document 1, when the fuel cell system normally stops, the water
sealing mechanism can seal the inside of the fuel cell system
(hydrogen generator). In contrast, in a case where the internal
pressure of the hydrogen generator is increased to a predetermined
pressure or higher by the water evaporation at the time of the
power outage, water sealing of the water sealing mechanism by a
water head difference is automatically lost, and the internal gas
can be discharged to the outside without the power supply. With
this, the internal pressure of the hydrogen generator at the time
of the power outage can be maintained at an appropriate level, and
failures of the devices by the increase in the internal pressure of
the hydrogen generator can be prevented.
[0015] Patent Document 1: Pamphlet of International Publication WO
2006/013917A1
[0016] Patent Document 2: Japanese Laid-Open Patent Application
Publication 2005-243330
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0017] However, in the case of the hydrogen generator described in
Patent Document 1, a carbon monoxide gas remaining in the hydrogen
generator is contained in the gas discharged to the atmosphere when
the water sealing of the water sealing mechanism is lost. In some
cases, there is a possibility that carbon monoxide which exceeds an
allowable concentration is discharged from the hydrogen
generator.
[0018] Also, in the case of the hydrogen generator described in
Patent Document 2, the carbon monoxide remaining in the hydrogen
generator is discharged to the atmosphere when opening the on-off
valve.
[0019] The present invention was made in view of these
circumstances, and an object of the present invention is to provide
a hydrogen generator capable of further suppressing the leakage of
the carbon monoxide, remaining in the hydrogen generator, as
compared to before in a case where the internal pressure of the
hydrogen generator is depressurized due to the water evaporation at
the time of at least one of the power outage and a normal stop
operation in which the power supply is not cut.
[0020] Another object of the present invention is to provide a fuel
cell system including the hydrogen generator.
Means for Solving the Problems
[0021] To solve the above problems, the present invention provides
a hydrogen generator including: a reformer configured to generate a
hydrogen-containing gas using a raw material and steam; a water
evaporator configured to supply the steam to the reformer; a
sealing device provided on a passage located downstream of the
reformer and configured to block a gas in the passage from flowing
to atmosphere; and a depressurizer provided on a passage located
upstream of the reformer and configured to release to the
atmosphere, pressure in the hydrogen generator which pressure is
increased by water evaporation in the water evaporator after the
sealing device is closed.
[0022] As above, by providing the depressurizer on the passage
located upstream of the reformer, an internal pressure of the
hydrogen generator can be released to an outside thereof while
further suppressing the leakage of carbon monoxide, remaining in
the hydrogen generator, as compared to before.
[0023] Moreover, the hydrogen generator of the present invention
may be configured such that the depressurizer is provided on the
passage which connects the water evaporator and the reformer.
[0024] In a case where the depressurizer is provided on the passage
located upstream of the water evaporator or the passage which
connects the reformer and the raw material supplier, a part of the
raw material in the passage or a part of the water in the passage
is discharged when releasing the internal pressure of the hydrogen
generator. Therefore, there is a possibility that at the time of
the next start-up, a time for the raw material supplied from the
raw material supplier or the water supplied from the water supplier
to reach the reformer becomes longer than usual. However, in the
case of the above configuration, this possibility is reduced.
[0025] Moreover, the hydrogen generator of the present invention
may be configured to further include a raw material supplier
configured to supply the raw material to the reformer, wherein the
depressurizer is provided on the passage which connects the raw
material supplier and the reformer.
[0026] There is a possibility that in a case where the
depressurizer is provided on the passage which connects the water
supplier and the water evaporator, ions dissolved in the water in
the passage deposit, and this causes malfunctions, such as
fixation. However, in the case of the above configuration, this
possibility is reduced.
[0027] Moreover, the hydrogen generator of the present invention
may be configured such that the depressurizer is provided on the
passage located upstream of the water evaporator.
[0028] With this configuration, the depressurizer is indirectly
communicated with the reformer via the water evaporator. Therefore,
as compared to a case where the depressurizer is directly
communicated with the reformer, the release of the steam in the
water evaporator is prioritized over the release of the
hydrogen-containing gas in the reformer, so that the leakage of the
carbon monoxide gas in the reformer can be further suppressed.
[0029] Moreover, as one example of the configuration in which the
depressurizer is provided on the passage located upstream of the
water evaporator, the hydrogen generator of the present invention
may be configured to include a water supplier configured to supply
water to the water evaporator, wherein the depressurizer is
provided on the passage which connects the water supplier and the
water evaporator.
[0030] There is a possibility that in a case where the
depressurizer is provided on the passage which connects the raw
material supplier and the water evaporator, the raw material in the
passage is discharged to the outside of the hydrogen generator when
releasing the internal pressure of the hydrogen generator. However,
in the case of the above configuration, this possibility is
reduced.
[0031] Moreover, as another example of the configuration in which
the depressurizer is provided on the passage located upstream of
the water evaporator, the hydrogen generator of the present
invention may be configured to further include a raw material
supplier configured to supply the raw material to the reformer,
wherein the depressurizer is provided on the passage which connects
the raw material supplier and the water evaporator.
[0032] There is a possibility that in a case where the
depressurizer is provided on the passage which connects the water
supplier and the water evaporator, ions dissolved in the water in
the passage deposit, and this causes malfunctions, such as the
fixation. However, in the case of the above configuration, this
possibility is reduced.
[0033] Moreover, the hydrogen generator of the present invention
may further include: a deodorizer configured to remove an odorous
component in the raw material supplied to the reformer; and an
on-off valve provided on a passage extending between the deodorizer
and the reformer, wherein: the on-off valve is configured to block
the gas from flowing from the reformer to the deodorizer when the
sealing device is closed; and the depressurizer is provided between
the deodorizer and the reformer.
[0034] The inflow of the steam to the deodorizer can be suppressed
by the action of the on-off valve. As a result, the performance
degradation of the deodorizer can be suppressed.
[0035] Moreover, in the hydrogen generator of the present
invention, the sealing device may be a normally closed valve.
[0036] With this, since the sealing device automatically closes
when the electric power supply to the hydrogen generator is cut,
the discharge of the hydrogen-containing gas in the reformer from
the downstream side of the reformer to the atmosphere is
suppressed, which is preferable.
[0037] Moreover, in the hydrogen generator of the present
invention, the depressurizer may be a valve including a relief
mechanism capable of releasing the pressure in the hydrogen
generator to the atmosphere in a case where the pressure in the
hydrogen generator is a first upper limit pressure or higher.
[0038] With this, the internal pressure of the hydrogen generator
can be released in a case where electrical control cannot be
carried out due to the power outage, or the like.
[0039] Moreover, in the hydrogen generator of the present
invention, the depressurizer may be a solenoid valve including a
spring sealing mechanism and may be configured to cancel sealing of
the spring sealing mechanism in a case where the pressure in the
hydrogen generator is the first upper limit pressure or higher.
[0040] With this, in a case where the electric control cannot be
carried out due to the power outage, or the like, and the gas
pressure in the hydrogen generator is the first upper limit
pressure or higher, the sealing of the spring sealing mechanism is
automatically canceled, so that depressurizing can be appropriately
executed.
[0041] Moreover, the hydrogen generator of the present invention
may further include: a pressure detector configured to detect the
pressure in the hydrogen generator sealed by the sealing device;
and a control unit configured to cause the sealing device to
release the pressure in the hydrogen generator to the atmosphere in
a case where the pressure detected by the pressure detector is
equal to or higher than a second upper limit pressure that is lower
than the first upper limit pressure.
[0042] With this, the internal pressure of the hydrogen generator
is released to the atmosphere before the pressure in the hydrogen
generator becomes the first upper limit pressure or higher.
Therefore, the deterioration of durability of the hydrogen
generator with respect to the internal pressure can be
suppressed.
[0043] Moreover, the hydrogen generator of the present invention
may be configured such that during at least one of a start-up
standby period of the hydrogen generator and a start-up operation
of the hydrogen generator, the solenoid valve carries out an
open-close operation once in at least one of a predetermined
cumulative operating time, a predetermined cumulative number of
times of operations, a predetermined period of time, and a
predetermined consecutive start-up standby time.
[0044] This suppresses the fixation between a valve seat and a
valve body (for example, rubber packing portions) of the spring
sealing mechanism of the solenoid valve due to adhesion
therebetween for a long period of time. Thus, it is possible to
reduce the possibility that in a case where the internal pressure
of the hydrogen generator is the first upper limit pressure or
higher, the depressurizing function of the solenoid valve cannot be
achieved.
[0045] Moreover, the hydrogen generator of the present invention
may further include: a pressure detector configured to detect the
pressure in the hydrogen generator sealed by the sealing device;
and a control unit, wherein the control unit may cause the on-off
valve to open in a case where the pressure detected by the pressure
detector is a second upper limit pressure or higher.
[0046] Moreover, in the hydrogen generator of the present
invention, the second upper limit pressure may be lower than the
first upper limit pressure.
[0047] With this, the internal pressure of the hydrogen generator
is released to the atmosphere before the pressure in the hydrogen
generator becomes the first upper limit pressure or higher.
Therefore, the deterioration of durability of the hydrogen
generator with respect to the internal pressure can be
suppressed.
[0048] Moreover, the hydrogen generator of the present invention
may further include: a falling slope passage through which the gas
discharged from the depressurizer is introduced downward; and a
receiver configured to receive the water discharged from a lower
end of the falling slope passage.
[0049] With this, it is possible to reduce the possibility that the
gas containing a large amount of steam discharged from the
depressurizer is directly discharged, and this causes the
deterioration and malfunction of the other components constituting
the hydrogen generator. Moreover, the volume of the gas decreases
by the steam condensation while the gas is flowing through the
falling slope passage or in the receiver. Therefore, rapid gas
discharge to the outside can be suppressed.
[0050] Moreover, the hydrogen generator of the present invention
may be configured such that: the receiver includes a water storing
portion configured to store the water and a discharging mechanism
configured to discharge the water stored in the water storing
portion; and condensed water is wasted to an outside of the
hydrogen generator by discharging the water using the discharging
mechanism.
[0051] Moreover, in the hydrogen generator of the present
invention, the receiver may include a releasing structure capable
of releasing to the atmosphere the gas discharged from the lower
end of the falling slope passage.
[0052] With this, in the receiver, the gas pressure discharged from
the inside of the hydrogen generator is released to the
atmosphere.
[0053] The present invention also provides a fuel cell system
including a fuel cell configured to generate electric power by
using the gas.
[0054] As above, since the fuel cell system includes as a standard
component the receiver (such as a hopper or a water tank) capable
of discharging to the outside of the system the water discharged
from respective components (such as the hydrogen generator and the
fuel cell) constituting the fuel cell system, the configuration for
discharging the condensed water to the outside can be simplified by
utilizing the receiver.
[0055] The above object, other objects, features and advantages of
the present invention will be made clear by the following detailed
explanation of preferred embodiments with reference to the attached
drawings.
EFFECTS OF THE INVENTION
[0056] The present invention can provide a hydrogen generator
capable of depressurizing the inside of the hydrogen generator at
the time of the stop of the hydrogen generator while further
suppressing the leakage of the carbon monoxide, remaining in the
inside of the hydrogen generator, as compared to before. In
addition, the present invention can provide a fuel cell system
including the hydrogen generator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 is a block diagram schematically showing a
configuration example of a hydrogen generator in Embodiment 1 of
the present invention.
[0058] FIG. 2 are diagrams showing a specific example of the
position of a depressurizer.
[0059] FIG. 3 is a block diagram schematically showing a
configuration example of a fuel cell system in Embodiment 2 of the
present invention.
[0060] FIG. 4 is a diagram schematically showing a configuration
example of the depressurizer.
[0061] FIG. 5 is a block diagram schematically showing a
configuration example of the fuel cell system in Modification
Example 6 of the present invention.
EXPLANATION OF REFERENCE NUMBERS
[0062] 1 reformer [0063] 2 combustor [0064] 3 depressurizer [0065]
4 water evaporator [0066] 5 water supplier [0067] 6 raw material
supplier [0068] 7 discharger [0069] 8 fuel cell [0070] 9 pressure
detector [0071] 10, 10A, 10B, 10C sealing device [0072] 22
condensed water tank [0073] 25 wall portion [0074] 26 hopper [0075]
26A discharging function [0076] 26B water storing portion [0077]
22C, 26C releasing structure [0078] 27, 27A falling slope passage
[0079] 30 desulfurizer [0080] 31 steam backflow prevention valve
(on-off valve) [0081] 32 falling slope pipe [0082] 33 horizontal
pipe [0083] 50 controller [0084] 100 hydrogen generator [0085] 110,
110A fuel cell system
BEST MODE FOR CARRYING OUT THE INVENTION
[0086] Hereinafter, best embodiments for carrying out the present
invention will be explained in detail in reference to the
drawings.
Embodiment 1
[0087] FIG. 1 is a block diagram schematically showing a
configuration example of a hydrogen generator in Embodiment 1 of
the present invention. FIG. 1 shows only components necessary for
explaining a hydrogen generator 100 of the present embodiment and
does not show components not directly related to the explanation of
the present embodiment.
[0088] As shown in FIG. 1, the hydrogen generator 100 of the
present embodiment includes a reformer 1.
[0089] The reformer 1 is a device which includes a reforming
catalyst body (not shown) for causing a steam-reforming reaction to
proceed and can generate a hydrogen-containing gas from a
hydrocarbon-based raw material, such as a city gas, LPG, or
kerosene, and water. In a case where the hydrogen generator 100 is
incorporated in a fuel cell system, the hydrogen-containing gas
supplied from the reformer 1 is utilized as a reactant gas of a
fuel cell.
[0090] As one example of a pressure detector configured to detect
the pressure in the hydrogen generator, a pressure detector 9
capable of detecting the pressure in the reformer 1 is provided for
the reformer 1. The pressure detector 9 may be a pressure gauge
configured to directly detect the pressure of the gas in the
reformer 1 or a temperature detector capable of indirectly
detecting the pressure of the gas in the reformer 1. For example,
to detect the temperature of the reformer 1, the reformer 1 is
normally provided with a temperature detector configured to detect
the temperature of the reforming catalyst body, the temperature of
a casing around the reforming catalyst body, or the temperature of
the hydrogen-containing gas having flowed through the reforming
catalyst body. The pressure of the gas in the hydrogen generator
can be estimated based on the temperature detected by the
temperature detector. As the temperature detector, a thermocouple
can be used. However, any temperature detector may be used as long
as it can appropriately detect the temperature of the reformer
1.
[0091] Moreover, if the pressure of the gas in the hydrogen
generator 100 and the time elapsed after the operation stop of the
hydrogen generator 100 are correlated with each other, the pressure
of the gas can be estimated by using a suitable timing device
(timer) as the pressure detector configured to indirectly detect
the pressure of the gas.
[0092] To be specific, the "pressure detector" in the present
specification is not limited to the pressure gauge, such as a
diaphragm, and may be constituted by each of various detectors
capable of directly or indirectly detecting the pressure of the
gas.
[0093] As shown in FIG. 1, the hydrogen generator 100 includes a
water supplier 5 and a water evaporator 4.
[0094] The water evaporator 4 is a device capable of evaporating
the water supplied from an outside thereof. The water evaporator 4
generates steam necessary for the steam-reforming reaction of the
reformer 1.
[0095] FIG. 1 shows an example in which the water evaporator 4 and
the reformer 1 are integrally formed. However, the water evaporator
4 and the reformer 1 may be separately formed and be coupled to
each other by a pipe. In this case, the water is evaporated outside
the reformer 1, and the steam is supplied to the reformer 1.
[0096] A heat energy necessary for the water evaporation in the
water evaporator 4 may be supplied from an outside of the hydrogen
generator 100. However, it is preferable to utilize remaining heat
of a heat medium (below-described flue gas) used for heating the
reformer 1, since this can improves an energy efficiency. For
example, the energy efficiency of the hydrogen generator 100 can be
improved by configuring the hydrogen generator 100 such that the
reformer 1 and the water evaporator 4 are integrally formed via a
suitable dividing member (not shown) to transfer the heat of the
flue gas (described below) to both the reformer 1 and the water
evaporator 4.
[0097] The water supplier 5 is a device capable of adjusting the
amount of water supplied to the water evaporator 4. For example, a
water pump can be used as the water supplier 5. However, any device
other than the water pump can be used as long as it can adjust the
amount of water supplied to the water evaporator 4.
[0098] As shown in FIG. 1, the hydrogen generator 100 includes a
combustor 2 as a heating device configured to heat the reformer
1.
[0099] Since the steam-reforming reaction in the reforming catalyst
body of the reformer 1 is an endothermic reaction, heat needs to be
applied to the reforming catalyst body to cause the reaction to
proceed. Therefore, the combustor 2 is configured to heat the
reforming catalyst body. As the combustor 2, a combustion burner
can be used. With this, the heat of the high-temperature flue gas
generated in the combustor 2 is applied to the reforming catalyst
body to heat the reforming catalyst body to a temperature suitable
for the steam-reforming reaction. A heating device other than the
combustion burner may be used to heat the reformer 1.
[0100] As a combustion fuel of the combustion burner, the raw
material supplied to the reformer 1 can be used. However, the other
combustible fuel (for example, a part of the hydrogen-containing
gas generated by the reformer 1) may be used.
[0101] As shown in FIG. 1, the hydrogen generator 100 includes a
raw material supplier 6.
[0102] The raw material supplier 6 is a device configured to adjust
the flow rate of the raw material (herein, a material gas, such as
a city gas) supplied to the reformer 1. For example, a booster pump
can be used as the raw material supplier 6. However, any device,
such as a flow rate control valve, other than the booster pump may
be used as long as it can adjust the amount of the raw material
supplied to the reformer 1.
[0103] In FIG. 1, the raw material is supplied from the raw
material supplier 6 to the water evaporator 4, and the water is
supplied from the water supplier 5 to the water evaporator 4. The
raw material and the steam are mixed in the water evaporator 4.
Then, this mixture gas is supplied from the water evaporator 4 to
the reformer 1. However, a method for supplying the mixture gas to
the reformer 1 is not limited to this. For example, a destination
to which the raw material supplier supplies the raw material may be
communicated with a passage extending between the water evaporator
and the reformer (see FIG. 2(b) described below). In this case, the
raw material and the steam having flowed out from the water
evaporator are mixed with each other in the passage extending
between the water evaporator and the reformer.
[0104] As shown in FIG. 1, the hydrogen generator 100 includes a
sealing device 10.
[0105] The sealing device 10 is a device capable of blocking a
communication between the passage including the reformer 1 located
upstream of the position of the sealing device 10 and the
atmosphere. Herein, the sealing device 10 is provided on a passage
located downstream of the water evaporator 4 and a depressurizer 3
(details thereof will be described below). To be specific, as shown
in FIG. 1, the sealing device 10 is provided on the passage which
is located downstream of the reformer 1 and through which the
hydrogen-containing gas flowing out from the reformer 1 flows. A
downstream end of this hydrogen-containing gas passage is
communicated with the atmosphere.
[0106] For example, the sealing device 10 can be constituted by a
solenoid valve (solenoid on-off valve) provided on a pipe
constituting a gas passage.
[0107] As shown in FIG. 1, the hydrogen generator 100 includes a
controller 50.
[0108] The controller 50 is constituted by a microprocessor, or the
like, and appropriately controls various operations of the hydrogen
generator 100. The controller 50 may be a single control unit as
shown in FIG. 1, or may be a group of a plurality of control units
which cooperate with one another.
[0109] Next, the configurations of the depressurizer 3 and a
discharger 7 that are features of the hydrogen generator 100 of the
present embodiment will be explained.
[0110] The depressurizer 3 of the hydrogen generator 100 is
configured to release an internal gas (herein, a gas containing the
steam as a major component) of the hydrogen generator 100 to the
atmosphere to reduce internal pressure of the hydrogen generator
100 in a case where the internal pressure of the hydrogen generator
100 is increased to a first upper limit pressure or higher by, for
example, the expansion of the volume of the steam. The first upper
limit pressure is defined as a value smaller than the upper limit
of the withstanding pressure of the hydrogen generator 100.
[0111] The depressurizer 3 is provided on the passage located
upstream of at least the reformer 1 to further suppress the leakage
of carbon monoxide, remaining in the reformer 1, to the outside
(atmosphere) of the hydrogen generator 100 as compared to before,
and to appropriately depressurize the inside of the hydrogen
generator 100. A specific position of the depressurizer 3 changes
depending on the method for supplying the mixture gas of the raw
material and the steam to the reformer 1. A specific example of the
position of the depressurizer 3 will be described below.
[0112] As the depressurizer 3, an escape valve (relief valve) of a
simple pressure escape mechanism (relief mechanism) utilizing
sealing of a spring pressure can be used. With this, the
depressurizer 3 can be simply configured. Moreover, the
depressurizer 3 can be configured by using the solenoid valve
provided in such a direction as to function as the pressure escape
mechanism (relief mechanism).
[0113] In the case of constituting the depressurizer 3 by the
solenoid valve, the solenoid valve is provided on the gas passage
in such a direction as to automatically open in a case where the
internal pressure of the hydrogen generator 100 is the first upper
limit pressure (set pressure of a spring sealing mechanism of the
solenoid valve) or higher, and automatically close in a case where
the pressure decreases.
[0114] With this, in a case where the increase in the internal
pressure of the hydrogen generator 100 with the sealing device 10
closed is not excessive, the internal pressure of the hydrogen
generator 100 is maintained to be equal to or lower than a spring
pressure (set pressure) of the spring sealing mechanism of the
solenoid valve, and the inside of the hydrogen generator 100 is
sealed by the spring sealing mechanism of the solenoid valve. In
contrast, in a case where the increase in the internal pressure of
the hydrogen generator 100 with the sealing device 10 closed is
excessive (in a case where the internal pressure of the hydrogen
generator 100 is the first upper limit pressure or higher), the
internal pressure of the hydrogen generator 100 becomes equal to or
higher than the spring pressure (set pressure) of the spring
sealing mechanism of the solenoid valve, and the inside of the
hydrogen generator 100 is temporarily open to the atmosphere by
canceling the spring sealing mechanism of the solenoid valve (by
forming a gap, through which the internal gas flows out, by the
internal pressure which presses the spring). With this, the
internal pressure of the hydrogen generator 100 can be decreased to
a pressure level lower than the first upper limit pressure.
[0115] Further, in at least one of (i) a start-up standby period
from when a stop operation of the hydrogen generator 100 is
completed to when a next start-up operation starts and (ii) a
start-up operation before starting supplying the water to the water
evaporator 4, the solenoid valve constituting the depressurizer 3
is forcibly caused to carry out an open-close operation at least
once by the controller 50 from a state where the solenoid valve is
closed. This suppresses fixation between a valve seat and a valve
body (for example, rubber packing portions) of the spring sealing
mechanism of the solenoid valve due to adhesion therebetween for a
long period of time. Thus, it is possible to reduce the possibility
that in a case where the internal pressure of the hydrogen
generator 100 is abnormally increased, a depressurizing function of
the solenoid valve cannot be achieved due to the fixation.
[0116] A timing at which the solenoid valve is forcibly caused to
carry out the open-close operation in any one of the start-up
standby period and the start-up operation before starting supplying
the water to the water evaporator 4 may be any timing as long as it
is before the start of the fixation of the spring sealing mechanism
of the solenoid valve. For example, the solenoid valve is forcibly
caused to periodically carry out the open-close operation once in
at least one of a predetermined cumulative operating time (50 hours
for example) of the hydrogen generator 100, a predetermined
cumulative number of times of operations (predetermined cumulative
number of starts, predetermined cumulative number of stops; for
example, eight starts) of the hydrogen generator 100, a
predetermined period of time (one week for example), and a
predetermined consecutive start-up standby time (one week for
example).
[0117] Here, if the high-temperature gas (gas containing the steam
as the major component; hereinafter may be abbreviated as "steam"
according to need) is discharged from the depressurizer 3 to the
atmosphere, various problems may occur (for example, a device may
malfunction since the device is exposed to the high-temperature
steam).
[0118] In the present embodiment, the discharger 7 is provided,
which is communicated with the depressurizer 3 via a passage
(hereinafter referred to as "falling slope passage"; not shown)
through which the high-temperature gas is introduced downward. The
discharger 7 serves as a receiver configured to receive condensed
water discharged from a lower end of the falling slope passage and
be able to discharge the condensed water to the outside. With this,
the gas containing the high-temperature steam is cooled down while
it flows through the falling slope passage and is in the discharger
7, and is discharged (wasted to the outside of the hydrogen
generator 100) as the condensed water from the discharger 7. Thus,
in the present embodiment, the gas discharged from the
depressurizer 3 is prevented from contacting the components of the
hydrogen generator 100 which components may deteriorate by the
contact with the high-temperature gas (steam).
[0119] Moreover, the pipe constituting the above-described falling
slope passage does not have to have a falling slope over the entire
length as long as it can achieve a drainage performance of the
pipe. To be specific, a heat exchange portion including a
horizontal portion and a complex pipe system may be incorporated
into a portion of the pipe.
[0120] Moreover, to discharge the gas pressure, discharged from the
depressurizer 3, to the atmosphere, it is preferable that the
discharger 7 include an atmosphere opening separately from a
drainage opening for drainage.
[0121] Next, specific examples of the position of the depressurizer
3 will be explained in reference to the drawings.
[0122] FIG. 2 are diagrams showing specific examples of the
position of the depressurizer. FIG. 2(a) shows the positions at
which the depressurizer 3 can be provided in the configuration in
which the raw material and the steam are mixed in the water
evaporator 4 to supply the mixture gas to the reformer 1. FIG. 2(b)
shows the positions at which the depressurizer 3 can be provided in
the configuration in which the raw material and the steam having
flowed out from the water evaporator 4 are mixed in the passage
communicated with the reformer 1 to supply the mixture gas to the
reformer 1.
[0123] In the former case (FIG. 2(a)), the depressurizer 3 may be
provided on a passage A extending between the water evaporator 4
and the reformer 1. In a case where the depressurizer 3 is provided
on the passage located upstream of the water evaporator 4, a part
of the raw material in the passage or a part of the water in the
passage is discharged when releasing the internal pressure of the
hydrogen generator 100. Therefore, there is a possibility that at
the time of the next start-up, a time for the raw material supplied
from the raw material supplier 6 or the water supplied from the
water supplier 5 to reach the reformer 1 becomes longer than usual.
However, in the case of the present configuration, such problem is
less likely to occur.
[0124] Moreover, the depressurizer 3 may be provided on the passage
located upstream of the water evaporator 4. With this, since the
depressurizer 3 is indirectly communicated with the reformer via
the water evaporator 4, the leakage of the gas (carbon monoxide) in
the reformer 1 when releasing the internal pressure of the hydrogen
generator 100 by the depressurizer 3 can be suppressed more than
the case where the depressurizer 3 is provided on the passage A
which connects the water evaporator 4 and the reformer 1.
[0125] One example of the passage located upstream of the water
evaporator 4 is a passage B extending between the water supplier 5
and the water evaporator 4. There is a possibility that in a case
where the depressurizer 3 is provided on a passage C, the
combustible raw material in the passage C is discharged to the
outside of the hydrogen generator 100 when releasing the internal
pressure of the hydrogen generator 100. However, in a case where
the depressurizer 3 is provided on the passage B, this possibility
is reduced.
[0126] Another example of the passage located upstream of the water
evaporator 4 is the passage C extending between the raw material
supplier 6 and the water evaporator 4. There is a possibility that
in a case where the depressurizer 3 is provided on the passage B,
ions dissolved in the water in the passage B deposit, and this
causes malfunctions, such as the fixation. However, in a case where
the depressurizer 3 is provided on the passage C, this possibility
is reduced.
[0127] In the latter case (FIG. 2(b)), the depressurizer 3 may be
provided on a passage D extending between the water evaporator 4
and the reformer 1. In a case where the depressurizer 3 is provided
on a passage E located upstream of the water evaporator 4 or a
passage F which connects the reformer 1 and the raw material
supplier 6, a part of the raw material in the passage or a part of
the water in the passage is discharged when releasing the internal
pressure of the hydrogen generator 100. Therefore, there is a
possibility that at the time of the next start-up, a time for the
raw material supplied from the raw material supplier 6 or the water
supplied from the water supplier 5 to reach the reformer 1 becomes
longer than usual. However, in the case of the present
configuration, this possibility is reduced.
[0128] Moreover, the depressurizer 3 may be provided on the passage
located upstream of the water evaporator 4. With this, since the
depressurizer 3 is indirectly communicated with the reformer via
the water evaporator 4, the leakage of the gas (carbon monoxide) in
the reformer 1 when releasing the internal pressure of the hydrogen
generator 100 by the depressurizer 3 can be suppressed more than
the case where the depressurizer 3 is provided on the passage D
which connects the water evaporator 4 and the reformer 1.
[0129] One example of the passage located upstream of the water
evaporator 4 is the passage E which connects the water supplier 5
and the water evaporator 4. There is a possibility that in a case
where the depressurizer 3 is provided on the passage F, the
combustible raw material in the passage F is discharged to the
outside of the hydrogen generator 100 when releasing the internal
pressure of the hydrogen generator 100. However, in a case where
the depressurizer 3 is provided on the passage E, this possibility
is reduced.
[0130] Moreover, the depressurizer 3 may be provided on the passage
F extending between the raw material supplier 6 and the reformer 1.
There is a possibility that in a case where the depressurizer 3 is
provided on the passage E, ions dissolved in the water in the
passage E deposit, and this causes malfunctions, such as the
fixation. However, in a case where the depressurizer 3 is provided
on the passage F, this possibility is reduced.
[0131] For ease of explanation of the position of the depressurizer
3, FIG. 2 show that the reformer 1 and the water evaporator 4 are
separately formed. However, as described above, it is preferable
that the reformer 1 and the water evaporator 4 be integrally
formed.
[0132] Next, operations (herein, a start-up operation and a normal
stop operation) of the hydrogen generator 100 of the present
embodiment will be explained.
[0133] In the start-up operation of the hydrogen generator 100, the
reformer 1 is heated by the combustor 2 such that a temperature
thereof is increased to a temperature suitable for generation of
the hydrogen-containing gas. To heat the reformer 1, the raw
material having been supplied through the reformer 1 to the
combustor 2 is combusted in the combustor 2. A passage through
which the raw material having flowed through the reformer 1 is
supplied to the combustor 2 is realized by connecting the
downstream end of the hydrogen-containing gas passage shown in FIG.
1 to the combustor 2. The reason why the raw material is caused to
flow through the reformer 1 is because the raw material heated by
the combustion heat of the combustor 2 is used as a heat medium for
increasing the temperature of the hydrogen generator 100.
Therefore, the raw material may be directly supplied to the
combustor 2 without being supplied through the reformer 1. In a
case where the raw material in the reformer 1 is heated to a
predetermined temperature or higher without the water, the
deposition of carbon contained in the raw material as a constituent
element occurs, this clogs the passage of the reformer 1, and
therefore, the reforming catalyst body deteriorates. On this
account, it is necessary to start supplying the steam to the
reformer 1 when the temperature of the reformer 1 is lower than the
predetermined temperature.
[0134] In the present embodiment, since the water is converted into
the steam using the heat of the combustor 2, the heat extracted
from the combustor 2 is applied to the reformer 1 and the water
evaporator 4 such that in a state where the temperature of the
reformer 1 is lower than the predetermined temperature, the water
evaporator 4 is increased to a temperature at which the water can
be evaporated.
[0135] In the present embodiment, the temperature at which the
deposition of carbon from the raw material occurs is set to
400.degree. C. However, this set temperature changes depending on
the configuration of the reformer 1 and the position of the
temperature detector. Therefore, any temperature other than the
above-described set temperature may be used as long as it does not
cause the deposition of carbon.
[0136] By supplying the raw material and the steam to the reformer
1, the reformer 1 starts generating the hydrogen-containing gas by
the steam-reforming reaction. The concentration of hydrogen and the
concentration of carbon monoxide in the gas generated in the
reformer 1 by the reforming reaction change depending on the
temperature of the reforming catalyst body. Therefore, after the
temperature in the reformer 1 is adequately increased, and the
highly-concentrated hydrogen in the hydrogen-containing gas starts
to be generated, the start-up operation is completed. Then, the
hydrogen-containing gas starts to be supplied to devices (fuel
cell, hydrogen tank, and the like) utilizing the
hydrogen-containing gas. The present embodiment has adopted a mode
in which only the reformer 1 is provided as a reactor in the
hydrogen generator 100. However, in a case where the carbon
monoxide concentration needs to be further reduced in the devices
utilizing the hydrogen-containing gas, the present embodiment may
adopt a mode in which a reactor (shift converter, or the like)
configured to reduce the carbon monoxide may be provided downstream
of the reformer 1.
[0137] In the normal stop operation in which the electric power
supply to the hydrogen generator 100 is not cut by power outage, a
breaker, or the like, the supply of the raw material and the supply
of the water to the hydrogen generator 100 are cut, and the
combustion operation of the combustor 2 is stopped, so that the
operation of the hydrogen generator 100 is stopped.
[0138] Here, immediately after the operation of the hydrogen
generator 100 is stopped, respective portions of the hydrogen
generator 100 are high in temperature. At this time, there is a
possibility that if the catalyst body, such as the reforming
catalyst body, contacts the air, the oxidative degradation of the
catalyst body occurs. For the purpose of appropriately preventing
the oxidative degradation of the catalyst, the input portions of
the hydrogen generator 100 are blocked, and the output portions
(for example, the sealing device 10 as the on-off valve) of the
hydrogen generator 100 are closed. Thus, with the
hydrogen-containing gas existing in the hydrogen generator 100, the
inside of the hydrogen generator 100 is sealed.
[0139] Immediately after the operation of the hydrogen generator
100 is stopped, the water remains in the water evaporator 4. If
such remaining water is evaporated by remaining heat of the water
evaporator 4, the internal pressure of the hydrogen generator 100
increases. In a case where the internal pressure is excessively
increased, the internal pressure may be released via the
depressurizer 3. However, in consideration of the durability of the
depressurizer 3 and the reduction in the pressure applied to the
components of the hydrogen generator 100, the hydrogen generator
100 is suitably depressurized in a case where the internal pressure
is equal to or higher than a second upper limit pressure that is
lower than the first upper limit pressure. The present embodiment
is set such that when the internal pressure of the hydrogen
generator 100 is increased to 3 kPa or higher, a depressurizing
operation in which the sealing of the sealing device 10 is canceled
by the controller 50 to cause the hydrogen generator 100 to be
communicated with the atmosphere is executed. However, since the
withstanding pressures of the devices are different from one
another depending on the characteristics of the devices, a pressure
threshold for executing the depressurizing operation does not have
to be 3 kPa but may be the other value. Moreover, the internal
pressure of the hydrogen generator 100 is released by the above
depressurizing operation when it is lower than that released by the
above depressurizing via the depressurizer 3. This is preferable
since the amount of gas discharged from the hydrogen generator 100
at once is reduced, and rapid gas discharge is suppressed.
[0140] Here, for example, in a case where the downstream end of the
hydrogen-containing gas passage shown in FIG. 1 is connected to the
combustor 2, the gas in the hydrogen generator 100 is released to
the combustor 2 by temporarily opening the sealing device 10
(on-off valve), so that the internal pressure of the hydrogen
generator 100 can be depressurized through a flue gas passage (not
shown) through which a flue gas discharged from the combustor 2
flows and which is communicated with the atmosphere. When releasing
the gas to the combustor 2, an air supplier (not shown) capable of
supplying the combustion air to the combustor 2 may be activated.
With this, even if the gas released to the combustor 2 contains the
hydrogen-containing gas, the combustible gas, such as hydrogen, and
the carbon monoxide are appropriately diluted by the air in the
combustor 2, and then discharged to the atmosphere. In this case,
it is preferable that to adequately dilute and reduce the
combustible gas and the carbon monoxide contained in the released
gas, the amount of air supplied from the air supplier be adjusted
to be larger than the amount of air supplied during a hydrogen
supplying operation of the hydrogen generator 100. A sirocco fan
can be used as the air supplier, but any air supplier can be used
as long as it can supply the air.
[0141] After the operation of the hydrogen generator 100 is
stopped, the temperatures of respective portions of the hydrogen
generator 100 gradually decrease with time. For example, while the
reformer 1 is operating, the internal temperature of the reformer 1
is increased to about 650.degree. C. Therefore, the internal gas of
the reformer 1 contracts as the internal temperature of the
reformer 1 decreases. Then, the internal pressure of the hydrogen
generator 100 also decreases. Therefore, the internal pressure of
the hydrogen generator 100 which pressure has been increased by the
volume expansion of the water evaporated by the remaining heat of
the hydrogen generator 100 (especially, the water evaporator 4, and
the reformer 1, the flue gas passage, and the like capable of
transferring heat to the water evaporator 4) needs to be released
by the depressurizing operation for a while after the operation of
the hydrogen generator 100 is stopped. However, when the
temperature in the hydrogen generator 100 becomes a predetermined
temperature (for example, 300.degree. C.) or lower, the internal
pressure of the hydrogen generator 100 is decreased to a negative
pressure that is lower than the atmospheric pressure. If the
internal pressure of the hydrogen generator 100 becomes an
excessive negative pressure, a load is applied to various devices
(such as the solenoid valve and the gas passages) of the hydrogen
generator 100, and this becomes a cause of malfunction of the
devices. Here, for the purpose of preventing the internal pressure
of the hydrogen generator 100 from becoming the excessive negative
pressure, when the internal pressure of the hydrogen generator 100
becomes lower than a predetermined pressure, the hydrogen generator
100 is pressurized, so that the internal pressure of the hydrogen
generator 100 is maintained to be equal to or higher than the
predetermined pressure. Such pressurizing is realized by supplying
the raw material to the hydrogen generator 100. Specifically, raw
material supply sources, such as a raw material infrastructure
(city gas for example) and a raw material tank (propane bomb for
example), usually have supply pressure. Therefore, by opening an
on-off valve (not shown) provided on a raw material supplying
passage, the reduction in the volume of the gas contracted in the
hydrogen generator 100 by the temperature decrease is compensated.
The present embodiment is configured such that the pressurizing
operation is carried out when the internal pressure of the hydrogen
generator 100 becomes equal to or lower than the atmospheric
pressure plus 0.3 kPa. However, since the withstanding pressures of
the devices are different depending on the characteristics of the
devices, the other condition may be adopted as long as it does not
cause the malfunction of the devices.
[0142] As a method for cooling down the reformer 1 (hydrogen
generator 100) after the combustion operation of the combustor 2 is
stopped, there are two methods: one is a method for executing as
one step of the stop operation a cooling operation of forcibly
cooling down the reformer 1 by activating the air supplier (sirocco
fan) to supply the air to the flue gas passage; the other is a
natural cooling method without executing the above forcible cooling
operation. The present embodiment adopts the former method.
However, the latter method or the other cooling method may be
adopted as long as it can maintain the internal pressure of the
hydrogen generator 100 within a predetermined range. The
depressurizing operation and the pressurizing operation are
suitably executed in at least one of the stop operation of the
hydrogen generator 100 or the start-up standby period of the
hydrogen generator 100.
[0143] Next, the following will describe the stop operation in a
case where the electric power supply to the hydrogen generator 100
is cut by the power outage, the breaker, or the like during the
start-up operation of the hydrogen generator 100 or the hydrogen
supplying operation of the hydrogen generator 100 (the stop
operation in an abnormal case).
[0144] In a case where the electric power supply to the hydrogen
generator 100 is cut, all of various normally closed valves
(solenoid valves configured to close by solenoid demagnetization
and open by solenoid excitation) capable of opening and closing the
input portions and output portions of the hydrogen generator 100
are closed. At the same time, the suppliers, such as the raw
material supplier 6 and the water supplier 5, stop operating. The
normally closed valves configured to open and close the output
portions include the sealing device 10.
[0145] Here, for a while after the water supplier 5 stops
operating, the water remaining in the pipe extending from the water
supplier 5 to the water evaporator 4 and the water in the water
evaporator 4 continue to be evaporated by the remaining heat of the
hydrogen generator 100 (especially, the water evaporator 4, and the
reformer 1, the flue gas passage, and the like capable of
transferring heat to the water evaporator 4). Therefore, the steam
is continuously generated in the hydrogen generator 100. Because of
the volume expansion caused by the generation of the steam, the
internal pressure of the hydrogen generator 100 sealed by the
sealing device 10 increases.
[0146] It is preferable that in a case where the internal pressure
of the hydrogen generator 100 is increased to the second upper
limit pressure or higher, the depressurizing operation of the
hydrogen generator 100 be carried out by the controller 50.
However, the electric power supply to the hydrogen generator 100 is
being cut by the power outage, the breaker, or the like, so that
the controller 50 cannot open or close the sealing device 10. To be
specific, the depressurizing operation using the sealing device 10
cannot be carried out.
[0147] In the present embodiment, in a case where the gas pressure
in the hydrogen generator 100 is excessively increased to the first
upper limit pressure (herein, 50 kPa) or higher, the water
evaporator 4 and the atmosphere are communicated with each other by
the relief mechanism of the depressurizer 3, so that the internal
pressure of the hydrogen generator 100 is released to the
atmosphere. Here, the hydrogen generator 100 of the present
embodiment is configured such that by providing the depressurizer 3
on the passage located upstream of the reformer 1, the steam that
is a cause of the increase in the internal pressure of the hydrogen
generator 100 can be successfully released to the outside while
further suppressing the leakage of the hydrogen-containing gas
(carbon monoxide), remaining in the hydrogen generator 100, as
compared to before. Herein, the first upper limit pressure is set
to 50 kPa. However, the withstanding pressures of the devices are
different from one another depending on the characteristics of the
devices, so that the other value may be adopted as the first upper
limit pressure as long as it does not cause the malfunction of the
devices.
[0148] In the device in which the reformer 1 and the water
evaporator 4 are integrally formed as in the present embodiment
(FIG. 1), it is favorable to provide the depressurizer 3 on the
passage located upstream of the reformer 1 and the water evaporator
4. With this, the steam can be preferentially discharged, and the
release of the hydrogen-containing gas (carbon monoxide gas) can be
further suppressed as compared to before. Meanwhile, in a case
where the reformer 1 and the water evaporator 4 are separately
formed and are coupled to each other by a suitable pipe, the
depressurizer 3 may be provided on the pipe extending between the
reformer 1 and the water evaporator 4.
[0149] Moreover, if the high-temperature steam is cooled down, the
steam condenses into the water, so that the volume of the gas to be
released to the outside can be contracted. Therefore, in the
present embodiment, the gas having flowed through the depressurizer
3 is not directly discharged to the atmosphere, but flows through
the above-described falling slope passage to be introduced into the
discharger 7 together with the condensed water generated by cooling
down the steam.
[0150] By using as the discharger 7 a receiver which is included in
the hydrogen generator 100 as a standard component and includes a
water storing portion and a discharge mechanism configured to
discharge the water stored in the water storing portion, the
configuration for discharging the condensed water to the outside of
the hydrogen generator 100 can be simplified. As will be described
in Embodiment 2, examples of the receiver as the standard component
are a condensed water tank configured to store the water recovered
from the flue gas of the combustor 2 and a hopper provided outside
a wall portion constituting the casing (not shown) of the hydrogen
generator 100.
Embodiment 2
[0151] FIG. 3 is a block diagram schematically showing a
configuration example of the fuel cell system in Embodiment 2 of
the present invention.
[0152] As shown in FIG. 3, the hydrogen generator 100 (the
explanations of the configuration and operation thereof are
omitted) described in Embodiment 1 is incorporated in a fuel cell
system 110 of the present embodiment. In the present embodiment,
the discharger 7 (see FIG. 1) of the hydrogen generator 100 is
constituted by a below-described hopper 26, and the sealing device
10 (see FIG. 1) of the hydrogen generator 100 is constituted by
below-described sealing devices 10A, 10B, and 10C.
[0153] As shown in FIG. 3, the fuel cell system 110 includes a fuel
cell 8 configured to generate electric power using the
hydrogen-containing gas supplied from the hydrogen generator 100
and the oxygen contained in the air (oxidizing gas). Since the
internal configuration of the fuel cell 8 is known, an explanation
thereof is omitted.
[0154] Although not shown in FIG. 3, a passage through which the
air is supplied to the fuel cell 8 is formed. The air as the
oxidizing gas is supplied from, for example, a blower through the
above passage to the fuel cell 8. Moreover, since the concentration
of the carbon monoxide in the hydrogen-containing gas having flowed
through the reformer 1 is high in the start-up operation of the
fuel cell system 110, the hydrogen-containing gas from the hydrogen
generator 100 is supplied to not the fuel cell 8 but the combustor
2 by a suitable switching valve (not shown) through a bypass
passage on which the sealing device 10C is provided. The combustor
2 combusts using the hydrogen-containing gas to generate the heat
necessary for the steam-reforming reaction in the reformer 1. When
the reformer 1 is adequately increased in temperature, the
concentration of the carbon monoxide in the hydrogen-containing gas
is lowered, and the highly-concentrated hydrogen is generated, the
hydrogen-containing gas starts to be supplied to the fuel cell 8
using the switching valve, and the fuel cell 8 generates electric
power by the reaction between the hydrogen-containing gas and the
air. At this time, the hydrogen-containing gas (anode off gas)
unconsumed for electric power generation in the fuel cell 8 and
released from the fuel cell 8 is supplied to the combustor 2 and
utilized as a combustion energy for heating the reforming catalyst
body of the reformer 1. Moreover, the electric power and the heat
can be generated in the electric power generation of the fuel cell
8. Therefore, while maintaining the temperature of the fuel cell 8
at a suitable temperature, the cooling water is circulated in the
fuel cell 8 to effectively extract the generated heat of the fuel
cell 8. Thus, the heat exchange with the cooling water is executed.
Then, the cooling water warmed up by the heat exchange is stored
in, for example, a hot water tank (not shown), and utilized as, for
example, hot water for domestic use.
[0155] Thus, the fuel cell system 110 of the present embodiment
realizes efficient electric power generation while effectively
utilizing the energy.
[0156] As shown in FIG. 3, the depressurizer 3 of the fuel cell
system 110 is coupled via a falling slope passage 27 to the hopper
26 capable of discharging unnecessary water from the fuel cell
system 110.
[0157] The hopper 26 includes a hollow water storing portion 26B
which is provided outside a wall portion 25 constituting the casing
of the fuel cell system 110, and is a receiver configured to
receive the steam and the condensed water of the steam discharged
from the lower end of the falling slope passage 27. Then, the
hopper 26 includes a discharging function 26A (drain hose for
example) configured to introduce overflow water in a condensed
water tank 22 of the fuel cell system 110 to the outside. The
condensed water tank 22 stores a certain amount of recovered water
by the adjustment of the amount of overflow water.
[0158] Meanwhile, the high-temperature gas from the depressurizer 3
is cooled down and condenses while flowing through the falling
slope passage 27. The hopper 26 also serves as a discharger
configured such that the condensed water is also wasted to the
outside, since the water is discharged using the discharging
function 26A capable of discharging the water stored in the water
storing portion 26B of the hopper 26.
[0159] Moreover, the hopper 26 further includes an releasing
structure 26C having an atmosphere opening capable of releasing to
the atmosphere the steam discharged from the lower end of the
falling slope passage 27.
[0160] In the operation of the fuel cell system 110, the reforming
water supplied to the water evaporator 4 and the cooling water used
to cool down the fuel cell 8 are used. Here, it is preferable that
the water in the flue gas of the combustor 2, the water in a
cathode off gas having flowed through a cathode of the fuel cell 8,
the water in the anode off gas having flowed through an anode of
the fuel cell 8, and the like be recovered, and such recovered
water be used as the water (reforming water, cooling water)
necessary in the fuel cell system 110.
[0161] Moreover, adopted as the hydrogen generator 100 is a mode in
which only the reformer 1 is provided. However, in a case where the
fuel cell 8 is a low-temperature type fuel cell (polymer
electrolyte fuel cell for example), adopted to reduce the carbon
monoxide concentration may be a mode in which a reactor (shift
converter, and the like) configured to reduce the carbon monoxide
is provided downstream of the reformer 1.
[0162] Moreover, adopted is a mode in which the bypass passage and
the sealing device 10C are provided to prevent the
hydrogen-containing gas whose carbon monoxide concentration is not
adequately lowered from being supplied to the fuel cell 8 in the
start-up operation of the fuel cell system. However, the bypass
passage and the sealing device may not be provided in a case where
the fuel cell is a fuel cell (for example, a high-temperature type
fuel cell, such as a SOFC) whose anode electrode is less likely to
be poisoned by the carbon monoxide.
[0163] Further, by providing at least the sealing device 10B in the
mode in which the bypass passage and the sealing device 10C are not
provided, it is possible to block the communication between the
atmosphere and each of the gas passages in both the hydrogen
generator 100 and the fuel cell 8. Therefore, the mode in which
only the sealing device 10B is provided may be adopted.
[0164] Next, the operations of the fuel cell system 110 of the
present embodiment will be described. Since the operations of the
hydrogen generator 100 have been described in detail in Embodiment
1, explanations of the operations related to the hydrogen generator
100 are omitted or outlined herein. Moreover, the start-up
operation of the fuel cell system 110 is omitted herein since it
can be understood by referring to the explanation in Embodiment 1.
The controller 50 can be used as a control unit for the entire
operation of the fuel cell system 100 of the present
embodiment.
[0165] In the normal stop operation in which the electric power
supply to the fuel cell system 110 is not cut by the power outage,
the breaker, or the like, the fuel cell system 110 is sealed by
sealing the input portions and output portions of the hydrogen
generator 100 and the input portion and output portion of the fuel
cell 8.
[0166] At this time, the communication between the hydrogen
generator 100 and the fuel cell 8 may be maintained. However, in
the present embodiment, the communication between the hydrogen
generator 100 and the fuel cell 8 is blocked by the sealing device
10A (solenoid valve). In this case, the output portion of the fuel
cell 8 is closed by the sealing device 10B (solenoid valve).
Moreover, the bypass passage that is one of the output portions of
the hydrogen generator 100 is closed by the sealing device 10C.
[0167] Then, with the fuel cell system 110 sealed, the volume
expansion occurs by the water evaporation caused by the remaining
heat of the hydrogen generator 100. Then, in a case where the
internal pressure in the hydrogen generator 100 is increased to the
second upper limit pressure or higher, executed is the
depressurizing operation of releasing the internal pressure of the
hydrogen generator 100 to the atmosphere by cancelling the sealing
of the sealing device 10C (on-off valve) by the controller 50.
Instead of this depressurizing operation, adopted may be a mode of
executing a depressurizing operation by cancelling the sealing of
the sealing device 10A and the sealing of the sealing device 10B
(by cancelling the sealing of the sealing device 10B when stopping
the sealing device 10A without sealing the sealing device 10A).
[0168] Moreover, in a case where the temperature of the hydrogen
generator 100 is decreased to decrease the internal pressure of the
hydrogen generator 100, the pressurizing operation is executed by
the controller 50 as with Embodiment 1. The depressurizing
operation and the pressurizing operation are suitably executed in
at least one of the stop operation of the fuel cell system 110 and
the start-up standby period of the fuel cell system 110.
[0169] Next, the following will describe the stop operation in a
case where the electric power supply to the fuel cell system 110 is
cut by the power outage, the breaker, or the like during the
start-up operation of the fuel cell system 110 or the hydrogen
supplying operation of the fuel cell system 110 (the stop operation
in an abnormal case).
[0170] In a case where the electric power supply to the fuel cell
system 110 is cut, all of various normally closed valves (sealing
devices 10A, 10B, and 10C for example) capable of opening and
closing the input portions and output portions of the gases (the
raw material, the hydrogen-containing gas, and the oxidizing gas)
and the reforming water of the fuel cell system 110 are closed. At
the same time, the suppliers, such as the raw material supplier 6
and the water supplier 5, stop operating.
[0171] As with Embodiment 1, for a while after the water supplier 5
stops operating, the water remaining in the pipe extending from the
water supplier 5 to the water evaporator 4 and the water in the
water evaporator 4 continue to be evaporated by the remaining heat
of the hydrogen generator 100. Therefore, the steam is continuously
generated in the hydrogen generator 100 of the fuel cell system
110. Because of the volume expansion caused by the generation of
the steam, the internal pressure of the hydrogen generator 100
sealed by the above-described sealing devices (sealing devices 10A,
10B, and 10C) increases.
[0172] It is preferable that in a case where the internal pressure
of the hydrogen generator 100 is increased to the second upper
limit pressure or higher, the depressurizing operation of the
hydrogen generator 100 be carried out by the controller 50.
[0173] However, in this case, the electric power supply to the fuel
cell system 110 is cut by the power outage, the breaker, or the
like, so that the open-close operations of the sealing devices 10A,
10B, and 10C cannot be carried out by the controller 50. To be
specific, the above-described depressurizing operation using the
sealing device 10C (or the sealing device 10A or 10B) cannot be
carried out.
[0174] In the present embodiment, in a case where the gas pressure
in the fuel cell system 110 is excessively increased to the first
upper limit pressure (herein, 50 kPa) or higher, the water
evaporator 4 and the atmosphere are communicated with each other by
the relief mechanism of the depressurizer 3, so that the internal
pressure of the hydrogen generator 100 is released to the
atmosphere. Here, the fuel cell system 110 of the present
embodiment is configured such that by providing the depressurizer 3
on the passage located upstream of the reformer 1, the steam that
is a cause of the increase in the internal pressure of the fuel
cell system 110 can be successfully released to the outside while
further suppressing the leakage of the hydrogen-containing gas
(carbon monoxide), remaining in the fuel cell system 110, as
compared to before. Herein, the first upper limit pressure is set
to 50 kPa. However, the withstanding pressures of the devices are
different from one another depending on the characteristics of the
devices, so that the other value may be adopted as the first upper
limit pressure as long as it does not cause the malfunction of the
devices.
[0175] In the device in which the reformer 1 and the water
evaporator 4 are integrally formed as in the present embodiment
(FIG. 3), it is favorable to provide the depressurizer 3 on the
passage located upstream of the reformer 1 and the water evaporator
4. With this, the steam can be preferentially discharged, and the
release of the hydrogen-containing gas (carbon monoxide) can be
further suppressed as compared to before. Meanwhile, in a case
where the reformer 1 and the water evaporator 4 are separately
formed and are coupled to each other by a suitable pipe, the
depressurizer 3 may be provided on the pipe extending between the
reformer 1 and the water evaporator 4.
[0176] Moreover, if the high-temperature steam is cooled down, the
steam condenses into the water, so that the volume of the gas to be
discharged to the outside can be contracted. Therefore, in the
present embodiment, the gas having flowed through the depressurizer
3 is not directly discharged to the atmosphere, but flows through
the passage (above-described falling slope passage 27) for
discharging the steam-containing gas to be introduced into the
hopper 26 together with the condensed water generated by cooling
down the steam. The water can be appropriately discharged using the
discharging function 26A (discharger).
[0177] Moreover, as in the present embodiment, in a case where the
fuel cell system 110 includes as a standard component the hopper 26
serving as the discharger capable of discharging to the outside of
the system the water discharged from respective components (such as
the hydrogen generator 100 and the fuel cell 8) of the fuel cell
system 110, the configuration for discharging to the outside the
water condensed from the gas discharged from the depressurizer 3
can be simplified by utilizing the hopper 26. Moreover, the volume
of the gas discharged from the releasing structure 26C of the
hopper 26 contracts since the steam in the gas condenses while the
gas is flowing in the passage for discharging the steam-containing
gas. Therefore, it is possible to suppress rapid gas discharge to
the outside of the fuel cell system 110. Further, the
high-temperature gas discharged from the depressurizer 3 is cooled
down while the gas is flowing through the passage for discharging
the steam-containing gas. Therefore, the risk of a user getting
burned by the gas discharged from the releasing structure 26C of
the hopper 26 to the outside of the fuel cell system 110 is
reduced.
Modification Example 1
[0178] Modification Example 1 will explain a configuration example
of the depressurizer 3 in a case where the depressurizer 3 is
provided on the raw material supplying passage (for example, the
passage C or the passage F shown in FIG. 2).
[0179] FIG. 4 is a diagram schematically showing the configuration
example of the depressurizer.
[0180] As shown in FIG. 4, in a case where the city gas is used as
the raw material, a desulfurizer 30 (one example of a deodorizer)
capable of removing a sulfur constituent (one example of an odorous
component for detecting the gas leakage) contained in the city gas
is provided on a horizontal pipe 33 constituting a passage located
downstream of the raw material supplier 6. Moreover, an on-off
valve 31 (steam backflow prevention valve 31 capable of preventing
the steam from flowing backward to the desulfurizer 30 side) is
provided on a portion of the horizontal pipe 33 which portion is
located downstream of the desulfurizer 30 and between the
desulfurizer 30 and the water evaporator 4 (reformer 1). The on-off
valve 31 is configured to block the flow of the gas from the
reformer 1 to the desulfurizer 30 when the sealing device 10 is
closed. There is a possibility that the steam flows backward to the
desulfurizer 30 due to the increase in the internal pressure of the
hydrogen generator 100 after the sealing device 10 is closed.
However, the inflow of the steam to the desulfurizer 30 is
suppressed by the action of the on-off valve 31. As a result, steam
adsorption by the desulfurizer 30 (one example of the deodorizer)
can be suppressed, so that the performance degradation of the
desulfurizer 30 (one example of the deodorizer) can be
suppressed.
[0181] As the on-off valve 31, a solenoid valve can be used in
addition to a simple-structure spring type check valve. In a case
where the solenoid valve is used as the on-off valve 31, in the
normal stop operation of the hydrogen generator 100 (fuel cell
system 110) in which the electric power supply is not cut, the
on-off valve 31 is closed by the controller 50 before the sealing
device 10 is closed. Thus, the inflow of the steam to the
desulfurizer 30 is suppressed. Moreover, it is preferable that the
on-off valve 31 be a normally closed type to deal with a case where
the electric power supply to the hydrogen generator 100 is cut.
This is because the on-off valve 31 is automatically closed
simultaneously with the sealing of the sealing device 10, so that
the inflow of the steam to the desulfurizer 30 is suppressed.
[0182] As above, Modification Example 1 is configured such that
with the sealing device 10 closed, the steam does not flow through
the raw material passage, located upstream of the on-off valve 31,
by the on-off valve 31. Therefore, Modification Example 1 has a
feature that the depressurizer 3 is provided on the raw material
passage located downstream of the on-off valve 31.
[0183] Specifically, as shown in FIG. 4, the depressurizer 3 is
provided on a portion of a falling slope passage 32 which portion
is adjacent to a connection position P where the horizontal pipe 33
and a falling slope pipe 32 constituting the falling slope passage
are connected to each other.
Modification Example 2
[0184] Embodiments 1 and 2 have described a mode in which the
depressurizing is carried out by the depressurizer 3 including the
relief mechanism in a case where the depressurizing operation using
the sealing device 10 by the controller 50 cannot be executed, such
as a case where the electric power supply is cut. However,
Modification Example 2 is configured such that even in the normal
stop operation in which the electric power supply is not cut, the
depressurizing operation using the relief mechanism of the
depressurizer 3 is carried out without executing the depressurizing
operation using the sealing device 10 by the controller 50.
Modification Example 3
[0185] Regarding the number of solenoid valves which are used as
the depressurizer 3 and each of which has the spring sealing
mechanism, the depressurizer 3 may be inexpensively realized by one
solenoid valve.
[0186] Moreover, two or more solenoid valves may be arranged in
series. With this, even if one of the solenoid valves breaks down
and does not close for some reasons, the other solenoid valve(s)
can close. Therefore, the depressurizer 3 can effectively function.
On this account, the reliability of the depressurizer 3
improves.
Modification Example 4
[0187] Embodiments 1 and 2 have described an example in which the
depressurizer 3 includes the pressure escape mechanism (relief
mechanism) utilizing the sealing of the spring pressure. However,
the present invention is not limited to this. For example, in a
case where the depressurizer 3 is an on-off valve which does not
have the relief mechanism, and the pressure detected by the
pressure detector 9 is the second upper limit pressure or higher in
the normal stop operation in which the electric power supply to the
hydrogen generator 100 is not cut, the controller 50 executes the
depressurizing operation by opening the on-off valve. In this case,
in a case where the electric power supply to the hydrogen generator
100 is cut, the internal pressure of the hydrogen generator 100
cannot be released, so that the pressure is applied to the hydrogen
generator, which is not preferable. However, as compared to a case
where the depressurizing is carried out from the downstream of the
reformer in a case where the electric power supply is not cut as in
the hydrogen generator described in Patent Document 2, it is
possible to further reduce the possibility that the
hydrogen-containing gas (carbon monoxide) leaks from the reformer 1
in the depressurizing operation.
Modification Example 5
[0188] Embodiments 1 and 2 have adopted a mode in which the sealing
of the sealing device 10 is canceled as the depressurizing
operation in a case where the internal pressure of the hydrogen
generator 100 is the first upper limit pressure or higher. However,
Modification Example 5 is configured such that in a case where the
depressurizer 3 is the solenoid valve having the spring sealing
mechanism, and the internal pressure of the hydrogen generator 100
is the second upper limit pressure or higher, the internal pressure
of the hydrogen generator 100 is released by opening the solenoid
valve by the controller 50. Also, Modification Example 5 is
configured such that in a case where the electric power supply is
cut, and the internal pressure of the hydrogen generator 100 is the
first upper limit pressure or higher, the internal pressure of the
hydrogen generator 100 is released from the depressurizer 3 by
cancelling the sealing of the spring sealing mechanism. With this,
the gas at the time of the depressurizing operation is released
from the passage located upstream of the reformer 1 even in the
normal stop operation in which the electric power supply is not
cut. Therefore, as compared to Embodiments 1 and 2, it is possible
to reduce the possibility that the hydrogen-containing gas (carbon
monoxide) leaks from the reformer 1 in the depressurizing
operation, which is preferable.
Modification Example 6
[0189] Embodiment 1 has exemplified the discharger 7 as the
receiver configured to receive the condensed water discharged
together with the gas discharged from the lower end of the falling
slope passage. Embodiment 2 exemplifies the hopper 26 as the
receiver configured to receive the condensed water obtained by
condensing the steam in the gas discharged from the lower end of
the falling slope passage 27.
[0190] FIG. 5 is a block diagram schematically showing a
configuration example of the fuel cell system in Modification
Example 6 of the present invention.
[0191] In a fuel cell system 110A of Modification Example 6, the
condensed water tank 22 of the fuel cell system 110A serves as the
receiver. To be specific, as shown in FIG. 5, the condensed water
tank 22 is a receiver configured to receive the condensed water
discharged from a lower end of a falling slope passage 27A. The
condensed water is discharged to an outside of the fuel cell system
110A by using an overflow function (discharging function) of the
condensed water tank 22. The gas (steam) is released to the
atmosphere by using an releasing structure 22C of the condensed
water tank 22.
[0192] From the foregoing explanation, many modifications and other
embodiments of the present invention are obvious to one skilled in
the art. Therefore, the foregoing explanation should be interpreted
only as an example, and is provided for the purpose of teaching the
best mode for carrying out the present invention to one skilled in
the art. The structures and/or functional details may be
substantially modified within the spirit of the present
invention.
INDUSTRIAL APPLICABILITY
[0193] In accordance with the hydrogen generator and fuel cell
system of the present invention, when the hydrogen generator is
stopped, such as when the electric power supply is cut, the inside
of the hydrogen generator can be depressurized while further
suppressing the leakage of the carbon monoxide gas in the hydrogen
generator as compared to before. Therefore, the present invention
is applicable to, for example, an electric power generating system
for domestic use.
* * * * *